Flowable CVD Gap Filling for Micro/Nano Optical Structures
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Solution Overview
Problem
Conventional methods for forming optical components in virtual and augmented reality display devices are limited by slow film deposition rates, particularly in atomic layer deposition processes, and there is a need for an improved method to efficiently fill micro/nano structures with contrasting refractive indices.
Innovation Solution
A method involving flowable chemical vapor deposition (FCVD) is used to form a second layer with a lower refractive index on a patterned first layer, utilizing a dual-zone showerhead to separate precursor gases and radicals, enabling deposition of a silicon dioxide layer that fills gaps and achieves uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If atomic layer deposition (ALD) process is used to form higher RI layer on patterned lower RI layer, then optical component with contrasting refractive indices is formed, but film deposition rate is very slow
Solution Approach 1:
The patent changes the deposition method from ALD to CVD, altering the process parameters to achieve faster deposition rates while maintaining the ability to form optical components with contrasting refractive indices. The CVD process allows for rapid film formation compared to the slow ALD process.
Solution Approach 2:
The patent replaces the ALD process with a CVD process, substituting one deposition mechanism with another that offers improved deposition rate. This substitution enables faster film formation while still achieving the required optical component structure.
2Manufacturing precision
If conventional lithography processes are used to pattern lower RI layer, then micro/nano structures with contrasting refractive indices are formed, but the process is time-consuming and low efficiency
Solution Approach 1:
The patent forms the lower RI layer with micro/nano structures first, then directly deposits the higher RI layer using CVD without requiring additional patterning steps. This preliminary formation of the base structure eliminates time-consuming sequential patterning operations.
Solution Approach 2:
The patent combines the formation of contrasting refractive index structures with a single CVD deposition step, merging multiple process steps into one efficient operation that reduces overall patterning time while maintaining manufacturing precision.
3Manufacturing precision
If slow ALD process is used for film deposition, then conformal coating is achieved, but productivity is reduced
Solution Approach 1:
The patent changes from ALD to CVD deposition, modifying the process parameters to achieve both conformal coating uniformity and improved deposition rate. The CVD process parameters are optimized to maintain coating quality while increasing productivity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The FCVD process allows for rapid filling of micro/nano structures with a flowable film, improving deposition uniformity and efficiency, and the resulting optical components can be used in augmented and virtual reality display devices, including waveguides and flat lenses.
Implementation Method 1
forming a second layer on the first layer by a flowable chemical vapor deposition process
Implementation Method 2
utilizing a dual-zone showerhead to separate precursor gases and radicals
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2D
AI summary
Embodiments of the present disclosure generally relate to a method for forming an optical component, for example, for a virtual reality or augmented reality display device. In one embodiment, the method includes forming a first layer having a pattern on a substrate, and the first layer has a first refractive index. The method further includes forming a second layer on the first layer by a flowable chemical vapor deposition (FCVD) process, and the second layer has a second refractive index less than the first refractive index.